#!/bin/sh

# Authors:
# - Moritz Warning <moritzwarning@web.de> (2016)
# - Zhong Jianxin <azuwis@gmail.com> (2014)
#
# See file LICENSE at the project root directory for license information.
#
# i3status.conf should contain:
# general {
#   output_format = i3bar
# }
#
# i3 config looks like this:
# bar {
#   status_command exec /usr/share/doc/i3status/contrib/net-speed.sh
# }
#
# Single interface:
# ifaces="eth0"
#
# Multiple interfaces:
# ifaces="eth0 wlan0"
#

# Auto detect interfaces
ifaces=$(ls /sys/class/net | grep -E '^(eno|enp|ens|enx|eth|wlan|wlp)')

last_time=0
last_rx=0
last_tx=0
rate=""

readable() {
    local bytes=$1
    local kib=$((bytes >> 10))
    if [ $kib -lt 0 ]; then
        echo "? K"
    elif [ $kib -gt 1024 ]; then
        local mib_int=$((kib >> 10))
        local mib_dec=$((kib % 1024 * 976 / 10000))
        if [ "$mib_dec" -lt 10 ]; then
            mib_dec="0${mib_dec}"
        fi
        echo "${mib_int}.${mib_dec} M"
    else
        echo "${kib} K"
    fi
}

update_rate() {
    local time=$(date +%s)
    local rx=0 tx=0 tmp_rx tmp_tx

    for iface in $ifaces; do
        read tmp_rx <"/sys/class/net/${iface}/statistics/rx_bytes"
        read tmp_tx <"/sys/class/net/${iface}/statistics/tx_bytes"
        rx=$((rx + tmp_rx))
        tx=$((tx + tmp_tx))
    done

    local interval=$(($time - $last_time))
    if [ $interval -gt 0 ]; then
        rate="$(readable $(((rx - last_rx) / interval)))↓ $(readable $(((tx - last_tx) / interval)))↑"
    else
        rate=""
    fi

    last_time=$time
    last_rx=$rx
    last_tx=$tx
}

i3status | (read line && echo "$line" && read line && echo "$line" && read line && echo "$line" && update_rate && while :; do
    read line
    update_rate
    echo ",[{\"full_text\":\"${rate}\" },${line#,\[}" || exit 1
done)
